Articles of footwear can include an upper and a sole assembly. The upper can include layers or sections of material that wrap about and cover a substantial portion of the wearer's foot and ankle. The upper can also include laces, straps, or the like for securing the footwear to the wearer's foot. The sole assembly can include an outsole and a midsole. The outsole can be a unitary piece of relatively high-friction material that provides traction. The midsole can include foam or other resilient material disposed between the outsole and the upper for providing cushioned support for the wearer.
Typically, the outsole and the midsole are fixed together with the midsole disposed between the upper and the outsole. As such, the compression, resilience, and other characteristics of the sole assembly are substantially the same, regardless of how the wearer is standing, how the leg and foot are positioned relative to each other, etc. Thus, some conventional sole assemblies may not be useful for some activities and/or for training the wearer to arrange the foot and leg in a desired posture.
For instance, a sprinter may train themselves to run in a certain posture to enhance running performance (e.g., to improve acceleration, etc.). However, because the sole assembly is substantially uniform, the sole assembly is unlikely to provide any feedback to the runner, and training can be more difficult.